1. Field of the Invention
The present invention relates to a working machine such as a hydraulic shovel.
2. Description of the Related Art
If, for example, a cooler housed in a machine room is large and the upper end thereof projects outward through a machine room cover that covers the machine room, a dome-like bonnet (engine hood) is attached to the upper surface of the machine room cover, and the machine room is thereby partly raised to house the cooler.
For example, an engine hood disclosed in Japanese Unexamined Utility Model Registration Application Publication No. 5-64244 includes a standard hood of standard specification and a frame-like bulk hood on which the standard hood can be placed. A choice can be made between a case where the standard hood is directly joined to the machine room cover and a case where the bulk hood to which the standard hood is joined is joined to the machine room cover, and the height of the engine hood can thereby be adjusted.
This type of bonnet is manufactured at low cost, is lightweight and sufficiently rigid, and is therefore often made by pressing a steel sheet. However, if the size of the bonnet is too large, for example, a steel sheet out of which the bonnet is made is difficult to obtain. Even if a steel sheet can be obtained, forming is difficult, and the increased size of the die significantly increases the cost of manufacturing.
So, such a large-sized bonnet is made, for example, by joining a plurality of steel sheets by welding. However, there are problems of the strength of welding areas, the increased number of processes and components, the difficulty in handling due to the increased weight, and so forth.
Since the engine hood of Japanese Unexamined Utility Model Registration Application Publication No. 5-64244 includes the bulk hood, the height can be adjusted using the standard hood as it is. Therefore, this engine hood is effective in solving the above problems.
However, this engine hood is joined to the machine room cover and is integrated with the machine room cover. Therefore, the maintenance of a cooler and the like housed in the engine hood is structurally difficult. The work needs to be performed, for example, with a door provided in the side surface of the machine room open, or with the entire engine hood removed. In particular, the inside of the hood significantly projecting from the machine room is difficult to check and to reach, and the maintenance work requires time and effort.